1. Field of the Invention
The present invention relates to a juice extractor or a juicer which extracts juice from food stuff by the compression method and more particularly to a grinder-type juicer which extracts juice by grinding and squeezing the food stuff such as vegetables between upper and lower plates.
2. Prior Art
Squeezing-type juicers are used to extract juice from vegetables, tubers, or fruits via compression. Such squeezing-type juicers have been initially proposed by the inventor of the present application, for example, in Korean Utility Model Registration Application No. 86-17672. However, in the past, centrifugation has been the main method of juice extraction used.
The centrifugation method is suitable for extracting juice from fruit, etc. However, in the case of extraction of juice from vegetables and tubers, which are high in fiber but have a low water content, the materials must be sliced, and even at a considerably high rotation speed, the extraction rate is not satisfactory. Moreover, materials such as heavy metals are discharged from the vegetables together with the residue due to centrifugal force, and there are some other problems in the centrifugation method.
To the contrary, the juicer proposed by the inventor of the present application, i.e., a squeezing-type juicer which uses a pair of gears, has the advantage of being designed so that the material may be sliced and then squeezed or simultaneously sliced and squeezed in order to extract-the juice. Thus, the juice extraction rate is several times higher than in juicers using the centrifugation method, and heavy metals do not become mixed in with the juice. Among them, dual-gear squeezing-type juicers currently account for the majority of market demand.
FIG. 1 shows a completed juicer which expands on the above-mentioned proposal of the inventor of the present application and embodies the device of Utility Model Registration No. 59191.
In FIG. 1, by means of a drive gear group T connected to a drive motor M, a pair of mutually interlocking rotary grinding gears K grind the material I which is inserted into a hopper H. When the ground material is moved into a juice-squeezing net D and squeezed, the squeezed juice J drops into a receptacle V via a juice-squeezing guide G1, and the residue R is discharged via the residue guide G2.
However, in this type of juicer, since grinding and squeezing of the inserted material I is carried out by the grinding gears K, a considerable load is applied on the grinding gears K; and a comparatively high-output drive motor M and a drive gear group T are necessary. Moreover, as the grinding gears K must be in the form of helical gears comprising a spiral-shaped cutting edge, high-precision machining is required, and in order to prevent abrasion of the cutting edge with use, special high-quality material of considerable strength must be used.
Furthermore, if the inserted materials contain a large amount of fiber such as pine needles or arrowroot, it is, unless the material to be inserted is divided up into small amounts, not only impossible to carry out proper squeezing of the juice, but the residue ground up between the grinding gears K or juice-squeezing net D becomes jammed, giving rise to the risk of damage to the mechanism, and the use of the juice-squeezing net D causes various problems in handling and washing.
On the other hand, at household appliance and health food stores where squeezing-type juicers are used, as grains or nuts such as soy beans, adzuki beans and adlai must be soaked in water or cooked before they are used for producing juice by conventional juicers or other kitchen purposes, this has an adverse effect on grinding efficiency.
In order to solve the above problems, the inventor of the present application proposed a grinder-type juicer as shown in FIG. 2 in Korean Patent Application No. 93-10436 filed on Jun. 14, 1993. This grinder-type juicer is equipped with various cutting lands L1 and L2, and it is designed so that inserted material I such as vegetables are inserted and ground between the grinding surfaces of an upper plate P1 and a lower plate P2 which rotate relative to each other.
This kind of grinder-type juicer is relatively easy to manufacture, shows high durability, and can efficiently grind and squeeze juice out of high-fiber inserted materials or grain. However, it does have one structural problem. In this type of juicer, the grinding surface between the upper plate P1 and the lower plate P2 faces upward and is in the shape of a convex cone; as a result, the juice and the residue from the ground inserted material cannot be separated and drop together under their own weight. For this reason, in order to separate the juice from the ground material I', a filtering sieve S or another independent separating device such as a centrifuge (not shown) becomes necessary. In the final analysis, therefore, no matter how favorable the grinding efficiency of the upper and lower plates P1 and P2, the juice-squeezing efficiency of conventional grinder-type juicers depends on the efficiency of the separating device used.